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Item Hyperspectral remote sensing for early detection of wild carrot in Carrot (Daucus carota) seed production : a feasibility study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Bhatia, Sunmeet SinghCarrot (Daucus carota) seed production is an important part of the NZ vegetable seed industry with exports of $33.4 million NZD in 2020. Most carrot seed production is based in the Canterbury region, but there is a desire by key stakeholders to expand carrot seed production in the Hawke’s Bay region of NZ. However, presence of weed wild carrot (Daucus carota subsp. carota) in the region acts as a significant constraint to carrot seed production. Wild carrot plants can crosspollinate with carrot crop plants, causing genetic contamination in a crop where genetic purity is of critical importance. The current weed management strategy of manual scouting and rouging is resource intensive and ineffective in achieving appropriate control of wild carrot in the region. Airborne hyperspectral remote sensing is a technology that has proven its ability in plant species identification and can do so at a high spatial scale in a short period of time. This makes the technology a promising candidate for a superior alternative weed control method. This project aimed to test the feasibility of the technology to identify wild carrot plants in carrot seed crop fields and nearby areas within the crop’s isolation distance (2000m). This involved creating spectral libraries of dominant plant species/materials, including wild carrot, in the area of interest. The methodology involved conducting a survey and collecting airborne hyperspectral data. Further, ground-based collection of GNSS enabled accurate GPS locations of wild carrot plants in the survey area, acted as training and validation data for subsequent classification analysis. The ground truth data was also used for a pixel composition analysis – which also helped understand the environmental context of wild carrot plants. The data was analysed in an image processing software (ENVI®, v5.6). The analysis involved two levels of classification algorithms. A first order classification – minimum distance classification (MDC) – was used to classify the data into broad land surface cover types. The classification was successful with an overall accuracy of 96%. The second order classification was a soft classification algorithm which employed spectral unmixing – mixture tuned matched-filtering (MTMF). This method allows sub-pixel classification when the target surface is smaller than pixel size, as in this case. MTMF helped create a model which predicted potential locations of wild carrot plants at a threshold level of 5% of pixel area (surface area - 0.05m²) and a producer’s accuracy of 70% (Omission error rate – 30%) for patches above the threshold surface area. These predicted locations were projected on appropriate RGB base layers to create wild carrot weed maps. The biggest limitation was likely the 1m² spatial resolution of the hyperspectral camera employed in the study, which dictated the 5% pixel threshold level. These detection threshold and accuracy levels are lower than in other similar studies, however they are likely acceptable in the current context and can help mitigate wild carrot damage in carrot seed production in the Hawke’s Bay. The study has helped identify areas of future research to further improve the detection threshold and accuracy levels. These include identifying relationships between environmental context related parameters and wild carrot manifestation, acquiring higher spatial resolution data (lower altitude flights, unmanned aerial vehicle (UAV) mounted cameras, deploying of image fusion techniques using separate high spectral (hyperspectral) and spatial resolution (RGB/multispectral) imagery.Item A study of the influence of spacing within rows and seed tuber size upon the yield of the potato crop : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science at Massey University, New Zealand(Massey University, 1966) Anang, HusinUndoubtedly there is a need for more intensive research on improving methods of growing potatoes. One aspect which has a major influence on plant population is seed spacing and seed size. The project reported herein was designed to study the effect of different levels of spacing and seed size, together with their interactions, on terminal yield of potato crops. In view of the need to study other important factors influencing yield, the investigation was extended to include the effects of seed spacing and size on growth and development of the crops.Item Selected defoliation studies on butternut Cucurbita moschata, Duchesne cv. Waltham : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Physiology at Massey University(Massey University, 1986) Syed Ibrahim, Syed MohdA field experiment was carried out in the summer 1985/84 at Massey University Campus, Palmerston, New Zealand, to study the effect of selective defoliation on both growth and partitioning of dry matter during reproductive growth in Butternut (Cucurbita moschata, Dunchesne). The plants were trained to grow toward one direction, with one main vine through regular pruning of side branching. Defoliations was carried out at early flowering growth stage, leaving the treated plants with one, two or three block of leaves, at different positions, with different combinations on the stem. Each block has equall number on node, determined at the time of treatment. Newly developed leaves within the defoliated plant section were regularly removed. Results showed that removal of basal leaves block significantly increased the total dry weight and yield by 25% and 30% respectively. This was attributed to the high unit leaf rate and leaf area duration in the later period. Removal of one or more block of leaves from other part of the stem, all reduced plant growth and yield The Butternut plants exhibited a very stable pattern of dry matter partitioning between their organs. The sign of "recovery" which resulted in the proportion of dry matter found in each organs similar to that of CON plants, was observed at the first harvest (7 days) after defoliation. Partitioning of dry matter to fruits was observed to become stronger toward the end of growing period irrespective of pattern of defoliations. The pattern of fruit distributions on the plant was strongly influenced by the position of leaves. At final harvest higher total fruit dry weight and fruit number was found on the stem section with leaves presence. High number of fruit abortions reduced the yield in the stem section without leaves. The overall plant growth was strongly influenced by the age and the total area of leaf present on the plant after defoliation. Plants with more proportion of younger leaves grew better than plants with older leaves.Item Understanding the light environment within a planar cordon cherry system and its relationship to fruit quality and fruit set : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticulture at Massey University, Palmerston North, New Zealand(Massey University, 2022) Scofield, ClaireNew planting systems for cherry trees being investigated in New Zealand, are using reduced inter-row spacing to increase overall light interception, and two-dimensional planar architecture for increasing light distribution through the canopy. As fruit quality is thought to be dependent on the proportional irradiance (light transmission) experienced by the tree’s reproductive structures, these new planting systems are expected to increase fruiting sites and in turn the yield, producing high-quality fruit throughout the canopy. However, in the case of cherries, the level of understanding around both the light environment, and fruit quality distribution using these systems is largely unknown. Therefore, eight-year-old ‘Sweetheart’ cherry trees trained as a planar cordon and spaced at either 1.5 m or 2 m between rows were used to investigate the effects of the light environment within the canopies over the 2020-2021 season on fruit set and fruit quality was evaluated at harvest. Light measurements at four vertical positions within these canopies were taken at 5-minute intervals, from flowering (November 2020) through to harvest (January 2021). Photosynthetically active radiation readings recorded were then used to calculate the daily light integral (DLI). The average canopy DLI for all positions and treatments was found to decrease from flowering through to harvest, using a best fit polynomial model, DLI started at 25 mol mˉ² dˉ¹, and ended the season around 5 mol mˉ² dˉ¹. Variation due to row spacings became evident later in the season, with average monthly DLI higher in the 2 m rows in November and December than in the 1.5 m rows. Vertical position within the canopy had a high correlation with light penetration, with the lowest vertical position (1 m from the ground) in a 2 m row having an almost equivalent mean light environment to the second highest (2 m from the ground) vertical position in a 1.5 m row spacing. Yield, soluble solids concentration (SSC), fruit set and leaf area were all shown to be positively influenced by increased DLI, while diameter was slightly negatively influenced. This influence was generally true for vertical position in the canopy also. Early season DLI had the greatest influence on yield, mid-season DLI had the greatest influence on SSC, and late season DLI had little influence on either fruit set/number or on fruit quality. Introducing reflective mulch into these planar canopy systems was found to improve the light penetration into the lower canopy, however only significantly in the 2 m row spacing. There was little to no influence on fruit quality, fruit set or return bloom.Item Growth studies with lettuce (Lactuca sativa L) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science in Plant Science at Massey University(Massey University, 1974) Lee, Kong KianIn a sand culture experiment carried out in a heated glasshouse, the effect of five levels of P (ranging from 7.75 p.p.m. - 124 p.p.m. on the growth of two cultivars of lettuce was examined. Samples were taken at weekly intervals for ten weeks and growth analysis, and chemical analysis of the whole plant were carried out for total N, P and K from the samples. Significant differences between cultivars were found for net assimilation rate and leaf area ratio, with a slightly higher relative growth rate in young 'Cobham Green' plants. 'Cobham Green' had a greater leaf area ratio but smaller net assimilation rate than 'Webb's Wonderful' . The higher relative growth rate of Cobham Green at the early stages of growth was mainly due to its higher leaf area ratio, but net assimilation rate became an important component during later growth stages, possibly as a result of mutual shading. Within each cultivar, however, the variation in relative growth rate was based on net assimilation rate rather than in leaf area ratio. Both dry weight and the percentage of total P increased with increase in P supply. The percentages of total N and K decreased towards the market maturity but no general trend was observed in the percentage of total P.Item Water stress and apple fruit quality : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University(Massey University, 1992) Moremong, MapasekaRegulated Deficit Initiation (RDI) has been used successfully in dry climates to control vegetative growth of fruit trees during the early part of the growing season without seriously disadvantaging fruit growth or quality. This project was undertaken as part of a study to investigate the feasibility and practicality of using the RDI concept in a humid fruit growing environment using Royal Gala apple trees. Treatments consisted of a lucerne cover crop, black polyethylene undertree covers and a within-row herbicide strip which is the normal commercial practice in New Zealand orchards. A full irrigation treatment (FI) was used on half the experimental trees and an RDI treatment was used on the other half of the trees. The RDI treatment consisted of withholding water until 105 days after full bloom, then using a full irrigation for the remainder of the season. Integration with depth of the soil moisture content (θ) (measured with a neutron probe) at the commencement of the experiment revealed 230 mm of water was stored in the top 900 mm of soil. Full irrigation resulted in θ increasing, with storage of about 250 mm 83 days after bloom and remaining at this level for the remainder of the season. The storage in the RDI treatments decreased in a linear manner until 58 days after bloom, after which it remained constant until initiation was started 105 days after bloom. The lucerne RDI (LRDI) treatment had a lower storage (105 mm) during this constant period than plastic RDI (PRDI), or herbicide (HRDI) treatments which both had a storage of 130 mm. The amount of water in the soil at this time for LRDI and for PRDI/HRDI was 42% and 52% of the total available capacity. Immediately after irrigation commenced on the RDI treatments, profile water storage returned to the values of the FI treatments remaining at these values for the rest of the season. Removal of water from the soil profile was not uniform. It appeared that lucerne removed moisture from the upper horizons first, before extracting it from the zone below 500 mm. Leaf water potentials (ψₑ) were lower in RDI treatments, when measured at midday (but not pre-dawn), than in FI treatments. Leaves from LRDI trees had lower ψₑ values than did leaves from PRDI and HRDI trees. Rate of fruit growth was reduced in all RDI treatments during the early part of the season, but returned to the same value as FI fruit once irrigation was resumed, except for LRDI fruit which did not attain the same growth rate of FI fruit. There were less large fruit and more small fruit from LRDI treatments than from other treatments where no significant effects on fruit size were measured. Fruit from RDI treatments were firmer, less mature and contained more soluble solids at harvest than FI fruit; some of these differences were maintained through 12 weeks storage at 4°C. There was no consistent effect of irrigation or cover treatment on fruit colour, mineral content or disease incidence at harvest or after storage. Vegetative growth, measured as pruning weights and the increment in trunk diameter, was significantly reduced by RDI treatments with LRDI causing the greatest reduction in pruning weight and PRDI inducing the smallest trunk diameter increase. The combined lucerne cover crop and RDI treatment was the most successful method found for reducing soil moisture in a humid climate. It also resulted in the greatest amount of stress being induced in these trees, reducing both vegetative growth - a desirable effect, but also fruit growth, a commercially undesirable effect. It is suggested that different methods of managing lucerne, or the use of less successful water extracting plants will need to be evaluated before recommending a successful, yet practical method of using the RDI concept in apple orchards growing in humid environments.Item Non-destructive and cost-effective 3D plant growth monitoring system in outdoor conditions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in School of Food and Advanced Technology at Massey University, Palmerston North, New Zealand(Massey University, 2022) Paturkar, Abhipray P.Plant growth monitoring is one of the crucial steps within plant phenotyping. Traditional manual measurement techniques are error-prone and destructive. In recent times there has been substantial progress in computer vision-based methods. Due to their non-destructive nature and increased accuracy, imaging techniques are becoming state-of-the-art in plant phenotyping. However, most of the associated cameras, sensors, and processors are expensive, resulting in their reduced applicability in this area. This thesis proposes a framework for low-cost plant growth monitoring. A novel, cost-effective and non-destructive 3D method is proposed. It uses a smartphone’s camera and is based on the structure-from-motion algorithm to construct 3D plant models. This algorithm uses several overlapped images to build the model. The modelling speed and quality largely depend on the number of input images used. It is challenging to select the right number of images to generate an accurate plant model - too few images might generate false points in the 3D point cloud, whereas too many images will result in redundant processing, which will inevitably increase computation time. An analytical method is proposed to determine the appropriate number of images for modelling to solve this problem. Once the 3D model is generated, it is essential to segment the various plant components such as leaves and stems to measure traits. The segmentation method needs to be able to work regardless of the particular plant architecture. This thesis proposes a segmentation method using Euclidean distance to segment the point cloud. Finally, plant traits for growth monitoring are measured: leaf length, leaf width, number of leaves, stem height, and leaf area. Methods to accurately measure leaf length, width and stem height when curled are proposed. To conclude, this thesis demonstrated that the proposed framework could monitor plant growth and calculate structure and growth parameters in different outdoor conditions. The framework was tested using five different plants with different architectures: cauliflower, lettuce, tomato, chilli, and maize. Hence, this framework is a potential alternative to costly state-of-the-art systems.Item The effect of plant density, cultivar and season on the growth and development of broccoli : a thesis presented in partial fulfilment of the requirements for the degree of Master in Horticultural Science (Vegetable Production) at Massey University(Massey University, 1995) Pinera, Danilo RTwo field trials (summer and winter) were conducted at the Plant Growth Unit (PGU) to investigate the effects of density and season of planting on different cultivars of broccoli. Different aspects of growth and development were studied including dry matter accumulation, leaf production, curd initiation and curd maturity. Polynomial regression equations were fitted to the primary data and resulted in typical growth curves from which growth analysis parameters were derived. The season of planting significantly effected the developmental stages of the crop. RGR calculated according to the functional approach declined linearly with time in both winter and summer trial. It was initially highest in the summer trial but declined much faster than in winter trial. One of the components of RGR, namely LAR also showed the reduction over time, in both summer and winter plantings. The other component, NAR decline with time in summer, but showed slight increase over time in the winter trial. LAR was consistently lower during the summer trial compared with the winter trial. This consistent reduction is associated mainly with a lower specific leaf weight (SLW) because plants have thicker leaves which may absorb more radiation and therefore be more efficient in dry matter production. Differences in growth between seasons can be explained primarily by differences in accumulated heat units. In this study, it was evident that the number of leaves produced varied with planting season. The higher the temperature regime the more leaves produced hence, leaf count per plant was slightly higher in the summer than during the winter season. The time of head initiation were affected by planting density for both season. In the summer planting, widely spaced plants had higher leaf areas, number of leaves produced and curd yield but in the winter planting showed no significant differences in the number of leaves produced and the curd weight per plant between densities. The final number of leaves at initiation time showed variations with season of planting which suggests that leaf number can be useful index for the morphological age of the plant at curd initiation stage. Curd initiation (an important developmental event) was found to be strongly influenced by temperature. The number of days from transplanting to curd initiation was shorter in summer and longer in winter season. Considering a normal time scale, variations in the number of days from planting to curd initiation until maturity for both season was influenced by the two developmental stages of the crop: 1) planting to curd initiation, 2) curd initiation up to maturity. It took almost twice as long period for the plant to initiate curd during winter than during summer and the time from curd initiation to maturity was longest during the winter. The potential of the plants to produce dry matter varied with season. Total dry matter production was considerably lower in the winter crop which strongly suggests that the lower the temperature regime, the lower the potential for dry matter production. The heat unit accumulation necessary to bring the crop to the same stage of maturity varied in such a manner that it was lower when the season was cool, and higher when the season was warm. Total biomass per unit area increased with later harvests in the summer planting. Density influenced the curd and total dry weight per plant only in the summer planting. Varietal differences were found for both season of planting. Cultivar Shogun, with the longer growing period, had the lowest dry weight per plant for both plantings.Item Temperature and atmosphere composition influence on colour change of apples : a dissertation presented in partial fulfilment of the requirements for a Masterate of Horticultural Science, Massey University, Palmerston North, New Zealand(Massey University, 1993) Dixon, JonathanIn apples colour is a major quality parameter used by consumers to determine apple maturity. A full understanding of the nature of the relationship between storage conditions and apple fruit colour change would be of advantage in formulating models to predict how changes to handling systems would affect fruit colour. While much is known in a general way about how environmental conditions affect colour change, little information is available to characterise the nature of the relationships between temperature, oxygen and carbon dioxide. The postharvest change in colour was measured for two export apple cultivars; Cox's Orange Pippin and Granny Smith. Previous research on these and other apple cultivars has determined that colour change is from green to yellow. The colour of Cox's Orange Pippin and Granny Smith apples were measured by subjective and objective methods during experiments to investigate the effect of temperature and atmosphere composition on colour change. The objective methods used were: chlorophyll extraction and colour using a Minolta chromameter. The subjective method was colour matching for Granny Smith using the NZAPMB maturity colour charts. When related to changes in chlorophyll, the principal skin pigment, the colour parameters used had non-linear relationships. Lightness, hue angle and colour chart score all reflect pigment changes occurring as apples change colour from green to yellow. Lightness values were the least variable followed by hue angle then colour chart score. All methods used showed more sensitivity to changes in chlorophyll content when chlorophyll content was low compared to when chlorophyll content was high. The objective measurements were highly correlated with the subjective measurements and the conclusion was that the use of hue angle or lightness to follow colour change in the skin of Granny Smith and Cox's Orange Pippin apples is an accurate indirect measure of chlorophyll and other pigments. The rate constant of colour change (k), measured using a declining exponential function, from green to yellow, at eleven temperatures over two seasons, two harvests per season and several growers was investigated in order to characterise the relationship between yellowing and temperature. All the methods of colour measurement used had the same relationship with temperature which was described by a modified form of the Arrenhius equation. Re-worked published data also fitted the modified Arrenhius equation. The modified Arrenhius equation was used to generate k for the various colour parameters measured (chlorophyll, hue angle, lightness and colour charts score). The value of k, as a function of temperature, increases slowly between 0°C and 6°C (the lag phase), increases exponentially between 6°C and 20°c and reaches a maximum at 25.3°C for Cox's Orange Pippin and 23.5°C for Granny Smith before declining. Pattern of response to temperature was the same for each cultivar although Granny Smith yellowed more slowly than Cox's Orange Pippin. For Cox's Orange Pippin apples more variation was accounted for by differences between growers than years or harvests within a year. For Granny Smith fruit most variation was accounted for by differences between years. Sixteen atmospheres were used each year for Cox's Orange Pippin and Granny Smith apples from one harvest in order to characterise the relationship between yellowing and oxygen or carbon dioxide. Cox's Orange Pippin and Granny Smith apples differ in their response to oxygen. For Cox's Orange Pippin the value of k as a function of oxygen level increased slowly from 0% to 6% and thereafter increased exponentially from 6% to 19%. This function may be sigmoidal as the k values increase slows above 17% oxygen. The relationship for Granny Smith was poorly defined by this function, k values increased slowly as the oxygen level rose. This could be due to a fundamental physiological or biochemical difference between these two cultivars. Each cultivar had a similar response to carbon dioxide, described by a declining exponential function, with the relationship for Granny Smith being better defined than for Cox's Orange Pippin. The relationship of carbon dioxide with colour change was poorly defined as the effects of oxygen on colour change were not removed from the analysis. Oxygen appears to have a greater influence on colour change than carbon dioxide. Atmospheres for Cox's Orange Pippin apples were not scrubbed for carbon dioxide in 1989 but were in 1990. The pattern of response to oxygen in the absence of levels of carbon dioxide above 1% in the atmosphere did not alter the sigmoidal relationship found. This may be evidence that the effect on yellowing by oxygen and carbon dioxide is by separate processes. Ethylene levels in the atmosphere appeared to have little effect on the rate of yellowing in all the atmospheres studied. The carbon dioxide and oxygen functions were combined into a single equation for use as a predictive model. The temperature function, the modified Arrenhius equation, and the atmosphere functions were combined into one equation to which different environmental values were added. The use of such a model and other practical applications for the information gathered for this thesis are discussed and a chart drawn comparing the hue angle, lightness and colour chart score to chlorophyll level.Item Nutrient solution management for greenhouse tomatoes : a multiple-case study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University(Massey University, 2006) Xu, MinhuaNutrient solution released from hydroponic greenhouse operations has been considered as a potential pollution source by New Zealand regional authorities. The Management of Nutrient Solutions Released from Greenhouses: A Code of Practice (COP) is designed to assist New Zealand greenhouse growers in managing nutrient solution release in hydroponic systems to comply with The Resource Management Act 1991 (RMA) and regional resource plans prepared by regional authorities to ensure that their constituents act appropriately. A multiple-case study was designed to investigate the nutrient solution management and disposal practices of New Zealand hydroponic greenhouse tomato growers and, further, to investigate whether or not these practices meet the guidelines set out in The Management of Nutrient Solutions Released from Greenhouses: A Code of Practice. Three hydroponic greenhouse properties that represent the current New Zealand greenhouse tomato industry were selected as case studies. How the greenhouse growers manage nutrient solution in these greenhouses was investigated by interviewing the growers. The results show that none of the case study growers fully met the guidelines given in the COP. However, recirculating growers manage nutrient solution better than do the run-to-waste grower in terms of reducing nutrient solution discharge frequency. They release less volume of nitrogen into the environment per 1000 kg of tomato produced in their recirculating growing systems. The research results indicate that high-technology recirculating grower could better satisfy the requirements set out in the COP. Low-technology run-to-waste growers are unlikely to meet those requirements due to their system design. Therefore, adopting a recirculating growing system is considered as a trend of the industries in the future.